At the age of 16, Beckwith had already captained Black Rock to the Federal League Under 18's premiership and the Demons had been forced to rush to sign him in September 1949 after getting wind of other clubs about to make an offer. The Age newspaper said Beckwith was "attracting more interest than John Coleman". He waited another year for his senior debut but quickly blossomed into a quality player.

He started as a centreman but did not shine in the role and was moved to defence. In a year where 19 players made their debuts, his performance in the backline earnt Beckwith the Best First Year Player award. Spending some time up the ground in his second year, Beckwith kicked the last eight goals of his career. He would never bag another over the last 144 games of his career.

Beckwith quickly blossomed into a back pocket specialist. There he became the master of the "kicking for touch" tactic. The club were so concerned about umpires cracking down on the practice the club even asked journalists not to write about it. Sharing a consistent play award in 1953 the club's annual reported made note his ability to beat bigger and taller players easily. In a season where the team won just three games it was a major achivement to be recognised for defensive play.

The Demons shocked the footballing world by charging to a grand final in 1954, and it wasn't for lack of effort by Beckwith that they were beaten by Footscray. He was one of the best for his side. The next year they got the formula right and won the flag - Beckwith voted Most Consistent Player for the year despite a pre-season injury and having to fly back from Adelaide to play in the early weeks of the year. In 1956 he had his second premiership and a Sid Anderson Medal for runner up in the Best and Fairest.

Promoted to captain in 1957 he, along with 21 year-old vice captain Ron Barassi formed the youngest leadership team in the VFL. It was said that his rendition of "It's A Grand Old Flag" at half-time of the Semi Final against Essendon, where Melbourne trailed by 48 points, inspired a comeback by the side that fell just short of a miraculous comeback.

After winning through via the Preliminary, Beckwith almost didn't play in the rematch. He was forced into a late fitness test on his groin to prove himself for the Grand Final. He passed and went on to lead his side to a thumping Grand Final victory. To cap off a great year he was named Best and Fairest.

Selected for the 1958 Victorian side Beckwith was forced to pull out due to injury. He would never represent his state, but he did play 18 club games that year and captained his side to another grand final - this time suffering defeat.

He remained an automatic selection in 1959, but missed the Round 15 loss to Footscray after requesting to be dropped to the Seconds so he could find some form. He soon returned and led his team to another flag.

The 1959 Grand Final saw the Premiership Cup introduced for the first time, giving Beckwith the honour of being the first captain to ever do a lap of honour with the cup. It was his fourth flag, but last as captain.

In 1960 the leadership of the club switched to Barassi, now with Beckwith as his deputy. Despite only playing 16 games for the season thanks to a broken hand suffered against Carlton in Round 11 he still managed to finish 3rd in the Best and Fairest, and won his fifth premiership as a player before retiring from VFL football.

Coaching

After five premierships as a player at Melbourne Beckwith joined Hampden League club Colac as coach for 1960 and led them to to two flags and two grand finals in his five years in the job.

He returned to the Demons as an assistant to Norm Smith in 1966 after being passed over for the vacant Richmond job left open by the enforced retirement of Len Smith at the end of 1965. He was offered the chance to coach succeed premiership coach Bob Davis at Geelong but informed the Cats that he was not interested as he had just moved back to Melbourne from Colac.

After two years as an assistant Beckwith eventually replaced one of the Smiths, but it was Norm in 1968 after the master coach had resigned after the 1967 season. Beckwith had already had a taste of the big time during the Round 15, 1967 game when Smith suffered heart pains and Beckwith was forced to coach the second half.

It was bad timing for the new coach, as the Demons had just finished the last remnants of their glory era and at the end of 1970 he was replaced by two time reserves premiership coach Ian Ridley.